This is a proposal to investigate how the animal-vegetal (A-V) axis is determined in the sea urchin embryo. A popular model is that the A-V axis is determined by the interaction of factors emanating from the animal and vegetal regions of the embryo. The Angerer laboratory studies the animal determinants, which are likely to be transcription factors arising from the egg that activate batteries of genes expressed in the animal region of the embryo. There are three objectives. The first objective is to determine whether there is a general mechanism that establishes the animal domain (non-vegetal transcription domain, or NTD) by cloning several factors that reside there. The second objective is to study the interactions between the animal and vegetal factors that establish a border between the domains. The third objective is to assess the role of BMP2/4 signaling in specifying the animal fates.